The regression tests have been adapted and extensively
modified for the 6.1 release of PostgreSQL.

Three new data types (datetime,
timespan, and circle)
have been added to the native set of PostgreSQL types. Points, boxes, paths, and
polygons have had their output formats made consistent across the
data types. The polygon output in misc.out has only been
spot-checked for correctness relative to the original regression
output.

PostgreSQL 6.1 introduces a
new, alternate optimizer which uses genetic algorithms. These algorithms introduce a
random behavior in the ordering of query results when the query
contains multiple qualifiers or multiple tables (giving the
optimizer a choice on order of evaluation). Several regression
tests have been modified to explicitly order the results, and
hence are insensitive to optimizer choices. A few regression
tests are for data types which are inherently unordered (e.g.
points and time intervals) and tests involving those types are
explicitly bracketed with set geqo to
'off' and reset geqo.

The interpretation of array specifiers (the curly braces
around atomic values) appears to have changed sometime after the
original regression tests were generated. The current ./expected/*.out files reflect this new
interpretation, which might not be correct!

The float8 regression test fails on at least some platforms.
This is due to differences in implementations of pow() and exp()
and the signaling mechanisms used for overflow and underflow
conditions.

The "random" results in the random
test should cause the "random" test to
be "failed", since the regression
tests are evaluated using a simple diff. However, "random" does not seem to produce random results
on my test machine (Linux/gcc/i686).